Electromechanical atomizer



Jan. 29, 1957 B. J. EISENKRAFT 2,779,623

ELECTROMECHANICAL. ATOMIZER Original Filed March 20, 1951 2 Sheets-Sheet 1 /NVEN TOR Jan 29, 1957 B. J. EISENKRAFT ELECTROMECHANICAL ATOMIZER Original Filed March 20, 1951 2 Sheets-Sheet 2 ELECTROMECHANICAL ATOMIZER Bernard J. Eisenkraft, Brooklyn, N. Y.

Continuation of abandoned application Serial No. 216,499, March 20, 1951. This application September 10, 1954, Serial No. 455,127

10 Claims. (Cl. 299-1) This invention relates to an electromechanical atomizer which is a vibrative device to disperse liquids into fine droplets.

This application is a continuation of my copending application for Electromechanical Atomizer and Spray Dryer, filed Mar. 20, 1951, Serial No. 216,499, now abandoned.

Vibrative types of atomizers operate on the principle of having a member with a rapidly moving surface upon which a liquid is caused to fall and be dispersed as a spray of fine droplets. This application relates particularly to that type of vibrative atomizer possessing a thin bar executing fiexural vibrations. One difficulty is their lack of dependability of operation which is a necessary factor for industrial purposes.

It is an object of the present invention to provide an atomizer which is operable by electromechanical means.

It is another object of the present invention to provide an atomizer which will by electromechanical means consistently atomize liquids in an efficient mannerand be subject to close operational control.

For other objects and for a better understanding of this invention reference may be had to the following detailed description taken in connection with the accompanying drawings in which Fig. 1 is a perspective view of the atomizer embodying the features of the present invention.

Fig. 2 is a longitudinal sectional view taken through the atomizer and as viewed on line 22 of Fig. 1.

Fig. 3 and Fig. 3A are fragmentary and perspective views of the operating parts of the atomizer free of the housing.

Fig. 4 is a longitudinal sectional view of the bar-nozzle at rest and the dotted portion describes a vibrating mode of the bar-nozzle.

Fig. 5 is a block diagram illustrating the path of the electrical and mechanical vibrations through parts of the invention.

Referring noW to the Figures 1, 2, 3, 3A, and 4, represents a base forming a part of a closed housing 11 having a front side cover 12 with an opening 13 therein. Within closed housing 11 is a reservoir 14 adapted to contain a liquid. The reservoir 14 can be fastened to the top of the casing and has an inlet pipe 15 with a cap 16 which can be removed to permit filling reservoir 14 with liquid to be atomized. Extending from reservoir 14 is a manifold pipe 17 and one ormore discharge pipes 18 each having a valve fixture 38 with a knob 39 thereon which can be turned to regulate the flow of liquid leaving discharge pipe 18. Discharge 18 .is fitted with nozzle 40 after valve 38 through which thincolumns or drops of liquid are discharged. Discharge pipes 18 will be arranged above anti-nodal portions 43 of the bar-nozzle On base 10 is power amplifier 34 with preamplifier and phase shifter 35 connected by line cord'21 and plug 22 to an electrical receptacle to receive electric current ied States Pate an anti-nodal point of maximum amplitude, when, as

hereafter described in this specification, bar-nozzle 19 is caused to vibrate. Magnetizable member 29 is fastened to that end of pivot lever 30 opposite to drive rod 31. Said magnetizable member 29 is attracted to magnet core 27 when said magnet core 27 is energized by electrical current. In this fashion maguetizable member 29 cooperates with magnet core 27 to effect the vibration of pivot lever 30, thus causing bar-nozzle 19to move with great rapidity and force so as to atomize impinging liquid from nozzle 41?.

It is well known in the art that at resonant mechanical frequencies, the amplitude of vibration of the bar nozzle 19 will be at a maximum. Any small deviation from said resonant frequencies sent by power amplifier 34 to the magnet core 27 will so decrease the vibrational amplitude of bar nozzle 19 so as to cause cessation of the atomizing action. To insure that the electrical oscillations be the same as the resonant mechanical vibrations as to frequency and phase, this invention provides the' following system. Electromagnetic pickup 45, in the manner shown in Figs. 2 and 4, is provided which consists of a small permanent magnet 24 upon which is wound a coil of fine wire 25. Electromagnetic pickup 45 is positioned under an anti-nodal point 43 of the bar-nozzle 19. Said anti-nodal point 43 is a point of maximum amplitude of vibrating bar-nozzle 19 as distinguished from nodal point 42 which is a point of zero amplitude of vibrating bar-nozzle 19. The bar-nozzle 19 is made of magnetic material. Alternatively, bar-nozzle 19 may be made of corrosion-proof non-magnetic material with magnetic member 23 fastened to said barnozzle 19 at an anti-nodal point 43 by any suitable means. Electromagnetic pickup 45 is placed under said anti-nodal point 43 at a distance from zero axis 44 of bar-nozzle 19 equal to slightly more than the maximum amplitude when said bar-nozzle 19 is vibrating. Thus when barnozzle 19 vibrates, it will induce electrical oscillations of similar frequency but of different phase in the electromagnetic pickup 45. Said phase difference follows from the well known Lenzs law of electromagnetic induction whereby the direction of the induced currents in a coil of wire must be such as to create a field opposing the relative motion that caused it. Wire 25 enclosed in cable 36, in the manner shown in Fig. 2, will carry these induced electrical oscillations to preamplifier and phase shifter 35, where said induced electrical oscillations are increased in amplitude and then properly phased in respect to the mechanical vibrations of bar-nozzle 19. Wire 46 then conducts said adjusted electrical oscillations to power amplifier 34 whereby said adjusted electrical oscillations are amplified further to actuate magnet core 27 via coil 28 and thus mechanically drive barnozzle 19. i i

it is believed that the design of electrical devices such as a preamplifier, a phase shifter, and a power amplifier for sonic frequencies are Well known in the art as exemplified in radio engineering texts and periodicals. An equivalent electrical system for driving a mechanical device may be found in the Bureau ofMines Report of Investigations 3702 of ,May 1943 entitled, An Automatic Frequency Controlled Oscillator and Amplifier for Driving Mechanical Vibrators by E. V. Potter. In

Patented Jan. 29, 1957 The point at which bar- 7 source for liquid atomization.

said report R. I. 3702 Fig. 12 represents a circuit diagram of a three stage preamplifier with a phase shifting network between the second and third stage. Note in Fig. 12 of R. I. 3702 the phase control adjustment is a dual potentiometer.

In the text The Radio Engineering Handbook third edition fourth impression, 1941 by Keith l-lenny, section 11 describes audio frequency amplifiers. Preamplifier 35 is referred to in this specification is an audio frequency amplifier of the class A type as discussed on page 360 of said text. Power amplifier 34 referra to in this specification is discussed on page 362 of said text and is an electrical device used to deliver electrical power to a utilization device such as n loudspeaker or other electromechanical transducer.

Referring now to Fig. of this specification for an operational discussion, the electrical circuit is placed into operation and set for high amplification. Noise at low levels inherent in the system is generated sending power to drive rod 31 over a wide frequency range. Bar-nozzle 19 will vibrate at many frequencies with minute amplitudes. However, at the resonant points bar-nozzle 19 will describe maximum vibrational amplitudes. Thus the electromagnetic pickup adjacent to bar-nozzle 19 will have induced in it small electrical oscillations of the resonant frequencies and negligible electrical oscillations of non-resonant frequencies. A selective action occurs. The resonant electrical oscillations are then amplified in the preamplifier, brought into proper phase in respect to the mechanical resonant vibrations by the phase shifter,

thence to the power amplifier where the resonant electrical oscillations are further amplified to drive the electromechanical transducer and bar-nozzle l9. Bar-nozzle 19 receiving reinforcing resonant mechanical vibrations increases its resonant vibrating amplitude. The system is self exciting. It was foundthat by varying the phase control different multiples of bar-nozzle resonant frequency could be tuned in. Liquid is then caused to fall onto bar-nozzle l9 and immediately be atomized off. By tuning the electrical system off resonance, atomization of the liquid ceased causing bar-nozzle l to flood.

During atomization the effective mass and thus the resonant mechanical frequency of bar-nozzle 1? changes. This is largely a result of moving liquid on the surface of bar-nozzle 19. However, the self excited system de scribed in this specification continually cooperates with bar-nozzle 1% to drive said bar-nozzle at its particular resonant mechanical frequency.

For a particular liquid being atomized it wasfound that the average droplet size of the resulting spray was inversely proportional to the multiple of the resonant mechanical frequency of bar-nozzle 19. That is to obtain a finer spray, one would tune in higher multiples of the resonant mechanical frequency.

Each anti-nodal point of bar-nozzle can act as a point Any liquid resting on nodal portions of bar-nozzle 19 is drawn into anti-nodal portions and atomized off. Thus with one bar-nozzle one can spray over an area depending upon the number of anti-nodes on bar-nozzle 19.

The efficiency of resonant vibrative atomizers is high for losses'occur only in the vibrating bar as internal friction and in the electrical system. Using transistors instead of vacuum tubes in the electrical system, the overall atomizing eificiency of a resonance vibrative atomizer as described in this invention is many times greater than .the efficiency of a conventional mechanical systei While various changes may be madc'in the detail construction, it shall be understood that such changes shall be Within the spirit and scope of the present invention as defined by the appended claims.

What is claimed is:

1. An atomizer for dispersing a liquid into fine droplets comprising a bar-nozzle, vibrating means to vibrate said bar-nozzle at its natural frequency, means to introduce liquid to said bar-nozzle, means to receive impulses from said vibrating bar-nozzle, and means to feed said impulses to said vibrating means.

2. An atomizer for dispersing a liquid into fine droplets comprising first means to contact and disperse said liquid, vibrating means to vibrate said first means, means to introduce said liquid into contact with said first means, means to receive impulses from said first means, and means to feed said impulses to said vibrating means.

3. An atomizer comprising a member, vibrating means to vibrate said member, delivery means to deliver liquid to be atomized to said member, means electrically responsive to the vibrations of said member, and means to place said last mentioned means in operative relationship with said vibrating means, whereby said member is kept vibrating at a resonant flexural mode.

4. An atomizer for dispersing a liquid into fine droplets comprising a bar nozzle, fluid delivery means to deliver liquid to a face of said bar nozzle, vibrating means to vibrate said bar nozzle, and adjustment means to receive impulses from said bar-nozzle and to feed said impulses to said vibrating means whereby to maintain said bar nozzle vibrating at a resonant flexural mode corresponding to the instantaneous effective mass of said bar nozzle.

5. An atomizer comprising a bar-nozzle, fluid delivery means to deliver liquid to a face of said bar-nozzle, vibrating means to vibrate said bar-nozzle, and adjustment means to maintain said bar-nozzle at a resonant iiexural mode corresponding to the instantaneous effective mass of said bar-nozzle, said adjustment means comprising first means to receive oscillatory impulses from said bar nozzle, second means to place said oscillatory impulses in phase with said vibrating bar-nozzle, and third means to transmit said phased oscillatory impulses to said vibrating bar nozzle.

6. An electromechanical atomizer comprising a barnozzle, fluid delivery means to deliver a liquid to a face of said bar-nozzle, vibrating means to vibrate said barnozzle, and adjustment means to maintain said bar-nozzle at a resonant flexural mode corresponding to the instantaneous effective mass of said bar-nozzle, said vibrating means comprising an electromechanical transducer, and said adjustment means comprising a magnetic member secured to said bar nozzle at an antinoclal portion thereof, an electromechanical pickup positioned within the zone of magnetic influence of said magnetic member, said electromechanical pickup being adapted to have induced therein electrical currents caused by the vibrations of said magnetic member, and a phase shifter electrically connected to said electromechanical transducer and adapted to place said induced electrical currents in phase with the vibrations of said bar nozzle.

7. An electromechanical atomizer for dispersing a liquid into fine droplets comprising a magnetic bar nozzle, fluid delivery means to deliver fluid to a face of said bar nozzle, an electromechanical transducer to vibrate said bar nozzle, an electromechanical pickup adjacent to an antinodal portion of said vibrating bar nozzle, said electromechanical pickup being adapted to have induced therein electrical currents caused by the vibrations of said bar nozzle, and a phase shifter electrically connected to said electromechanical transducer and adapted to place said induced electrical currents in phase with the vibrations of said bar nozzle, whereby the vibrations of said bar nozzle are maintained at a resonant flexural mode corresponding to the instantaneous effective mass of said bar nozzle.

8. An electromechanical atomizer for dispersing a liquid into fine droplets comprising a magnetic vibrating bar nozzle, means to deliver liquid to said bar nozzle, means 7 to receive induced alternating electrical impulses from an antinodal portion of said bar nozzle, means to place said alternating electrical impulses in phase with the vibrations of said bar nozzle, and means in operable relationship with said vibrating bar nozzle to feed said phased electrical impulses to said bar nozzle in the form of mechanical impulses.

9. The method of operating an electromechanical atomizer of the vibrating bar nozzle type comprising the steps of vibrating the bar nozzle at a resonant flexural mode by means of an electromechanical transducer, in troducing liquid to a face of the bar nozzle thereby changing the efiective mass of said bar nozzle, receiving alternating electrical impulses from an antinoclal portion of said bar nozzle, placing said alternating electrical impulses in phase with the mechanical vibrations of said bar nozzle, and feeding said phased alternating electrical impulses to said electromechanical transducer.

10. The method of atomizing fluid comprising vibrating a fluid dispersing member, introducing a fluid to be dispersed into contact with the fluid dispersing member, receiving oscillating impulses from an an'tinodal portion of the fluid dispersing member, and causing the oscillating impulses to vibrate the fluid dispersing member at a resonant flexural mode corresponding to its instantaneous effective mass.

References Cited in the file of this patent UNITED STATES PATENTS 862,856 Tygard Aug. 6, 1907 2,420,691 Vang May 20, 1947 2,453,595 Rosenthal Nov. 9, 1948 2,646,261 Poirot July 21, 1953 

